
When you change down, the engine has to spin faster than it was. If you simply drop the clutch, the difference gets resolved by brute force: the engine brakes the driven wheels abruptly.
In a rear-wheel-drive car, hard on the brakes and starting to turn, that's the worst possible moment. The rear axle is already unloaded by weight transfer; adding a sudden, uneven braking force to it is the recipe for a spin.
Heel and toe solves that: you blip the throttle while braking, so the engine is already spinning at the right speed when you release the clutch. Engagement is smooth and the car never notices.
It all happens at once, which is why it looks hard. Broken down:
The part people get wrong most: brake pressure must stay constant throughout. If you ease off the brake as you blip, you've moved your braking point without meaning to and you'll run wide.
Trying it straight away at pace guarantees frustration. This works:
How to know you're doing it right: listen to the engine and watch the car. Done well, there's no jolt as the clutch comes up and the revs rise to the new gear's value without a step. Done badly, you feel a shudder and the rear moves.
It helps a lot to adjust the throttle pedal height so it sits close to the brake: if they're far apart, the movement is awkward because of geometry, not technique.
Where it does matter a lot: road cars and classics with a manual gearbox, and especially rear-wheel-drive ones with a big engine. There the difference between doing it and not doing it shows in the telemetry and in your hands.
Once the movement comes without thinking, the natural next step is trail braking: both happen in the same part of the corner and they complement each other.
With a sequential or dual-clutch gearbox, no: the car manages the engagement. You need it in cars with a manual gearbox and a clutch, which in a sim with a varied car list is quite a few.
The full movement needs three pedals. Without a clutch you can still do the useful part — blipping the throttle on the downshift — and the car will already feel more settled.
By itself, barely. What it gives you is stability on entry, and that lets you brake later and trust the car, which is time.
Because in older cars the pedals were arranged so you braked with the ball of your foot and blipped with your heel. Today it's usually done with the ball on the brake and the side of the foot on the throttle.
What it is, why it rotates the car, how to practise it and the mistakes that end in a spin.
Read →What each click does, how it shows up at the rear axle and how to find your value.
Read →What each parameter does, what order to touch them in and how to spot clipping.
Read →On the 24/7 you can drive whatever you like. A manual-gearbox car is where this really shows.